public class ReplaceCheck
{
   /**
      A method to replace letters as follows:
      the letter e becomes 3, the letter i becomes 1,
      the letter l becomes 7, and the letter o becomes 0.
      @param str a string
      @return the string with the characters replaced
   */
   public static String replace(String str)
   {
      str=str.replace("e","3");
      str=str.replace("i","1");
      str=str.replace("l","7");
      str=str.replace("o","0");
      return str;
   }
}